High voltage transients caused by lightning strikes have the ability to easily destroy semiconductor junctions, and thus, cause equipment failure and loss. A lightning strike close to data lines can also cause induced ground currents that can also do serious damage. The AL-D4W-05 high performance lightning protector provides superior protection of RS-422, RS485 or other 5-volt data lines from these transients or surges. The low capacitance diode array assures that the RS-422/485 signals will not be degraded by the suppressor. This is in comparison to protectors based on high capacitance TVS diodes. The unit will protect two full duplex RS-422 data line or four half duplex RS-485 data lines. For more complete protection, two units should be used, one on each end of the line. The compact weather resistant housing features a lockable hinged cover and break-away holes are provided on the rear of the enclosure for mounting. The cable grommet may be adjusted to cable size and is removable.